MOSSBAUER SPECTROSCOPIC STUDY OF IODINE-DOPED POLYVINYL-ALCOHOL FILMS

Iodine-doped polyvinyl-alcohol(PVA) films were studied at 16 K using the Mossbauer resonance of I-129. Experiments were done for the PVA films with or without boric acid, stretched or not, and doped with iodine only or co-doped with iodine and bromine. For the iodine-doped PVA films without boric acid, a major iodine species is I-. The addition of boric acid causes the formation of linear polyiodides with symmetrical charge population, I3- and I5-, and the stretch of the films increases the abundance ratio of I5-. From the analysis of the intensity ratio of the quadrupole split lines, it was confirmed that the linear polyiodides, I3- and I5-, lie parallel to the stretching direction. For iodine and bromine co-doped stretched films with boric acid iodine-exists as the central ion in the form of linear IBr2-.